Science

Double denim: How old jeans might gain a new life as artificial bone cartilage

Double denim: How old jeans mi...
New research from Deakin University could see denim repurposed as artificial cartilage
New research from Deakin University could see denim repurposed as artificial cartilage
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Dr Noelene Byrne, a scientist at Deakin University's school of engineering has developed a method for repurposing denim as bioscaffold for artificial cartilage
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Dr Noelene Byrne, a scientist at Deakin University's school of engineering has developed a method for repurposing denim as bioscaffold for artificial cartilage
New research from Deakin University could see denim repurposed as artificial cartilage
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New research from Deakin University could see denim repurposed as artificial cartilage
An aerogel sample made from dissolved denim
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An aerogel sample made from dissolved denim
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Scientists at Australia's Deakin University have come up with a potential new way to reclaim some of the tremendous waste generated by the fashion industry. The team has developed a method that reduces discarded denim to the building blocks for artificial cartilage, something that, with further development, could become an advanced tool for performing joint reconstructions in humans.

The work was led by Dr Noelene Byrne, a scientist at Deakin's School of Engineering, and involves first applying a liquid solvent to dissolve the denim. Byrne tells us this solvent was developed in-house and she won't share its components right now for intellectual property purposes, but it has the effect of reducing the denim to cellulose.

"Cellulose is a versatile renewable material, so we can use liquid solvents on waste denim to allow it to be dissolved and regenerated into an aerogel, or a variety of different forms," she says. "Aerogels are a class of advanced materials with very low density, sometimes referred to as 'frozen smoke' or 'solid smoke,' and because of this low density they make excellent materials for bioscaffolding, absorption or filtration."

Aerogels formed from cellulose are nothing new, but nobody had ever tried making it with a cellulose sourced from denim before. The team found that in doing so, it produced an aerogel with a unique porous structure, featuring vertical nanoscopic tunnels throughout. The team believes the sticky nature of the denim-based cellulose is why these tunnels form, but whatever the reason, the material they are left with is perfectly formed for use as artificial cartilage.

An aerogel sample made from dissolved denim
An aerogel sample made from dissolved denim

"That's exactly what cartilage looks like – you can't 3D print that material – and now we can shape and tune the aerogel to manipulate the size and distribution of the tunnels to make the ideal shape," says Byrne.

The team is now working with scientists in the university's materials department to develop the aerogel further for these purposes. Byrne says the preliminary data suggests the denim-based aerogels out-perform regular cellulose aerogels. Other potential applications include membranes used in water filtration systems and batteries, though artificial cartilage is a primary focus.

"The remarkable similarity in the pore network structure of these aerogels and cartilage tissues – even down to the dimensions, orientations, and density distribution of pore channels – enables these materials to replicate a special type of 'weeping' lubrication mechanism used by cartilage to protect against wear and damage," said Dr Wren Greene, from Deakin's Institute for Frontier Materials.

Though the amount of denim this approach could save from landfill is likely to be minimal, at least at first, the team says its method could form a blueprint for smarter recycling methods that prove more cost-effective than existing approaches.

"One of the main drawbacks of textile recycling efforts is that any advanced technique requires the use of chemicals, which can then make the procedure less cost-effective," says Byrne. "We use environmentally-friendly chemicals, and by upcycling our approach to create a more advanced material we can address the limitations affecting other less cost-effective methods. We are now entering pilot-scale trials and look to be at commercial scale within three to five years with industry support."

Source: Deakin University

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2 comments
michael_dowling
Artificial cartilage would be a godsend to people with osteoarthritis. Hip replacements are a horrible alternative,as they have a limited life,and people who once ran for exercise have to stop running,as the artificial joint can't endure the strain. God help those who fall and break the implant,as they are looking at major surgery with no guarantees of success stabilizing what's left of the joint.
Ralf Biernacki
While I think artificial cartilage would be a godsend, I can't help thinking there is something fishy about this supposed invention. For one thing, how would denim-derived cellulose be different than any other cotton, and supposedly "sticky"? That's not a technical description. Second, even if the aerogel (does cellulose gel in the first place?) has similar "vertical" porosity (which way is "vertical" in a chunk of material?) it hardly has the same mechanical properties, which for cartilage are very demanding. Thirdly, aerogels are gas-filled, and cannot remain so in the wet, repeatedly compressed environment of a joint. Such material will outgas, absorb moisture, and collapse. Fourth, joints are lubricated by synovial fluid secreted by the inner lining of the bursa, which does not pass through the cartilage, neither through "weeping lubrication" nor otherwise. Fifth there is the secret, but "enviromentally friendly" solvent---what does it dissolve? Denim is nearly pure cellulose, not held together chemically but through mechanical friction between cellulose fibers. All these, as well as other misstatements and the nebulous language make me suspect a scam, or at best a publicity stunt.